1. Field of Invention
The present invention relates to a pixel circuit, and more particularly relates to an AMOLED voltage type compensation pixel circuit.
2. Description of Related Art
FIG. 1 shows an organic light emitting diode pixel circuit of the prior art. The pixel circuit is a voltage type compensation pixel circuit. The pixel circuit has an organic light emitting diode 180, a first transistor 170, a driving transistor 130, a capacitor 150, and a second transistor 110. The first transistor 170 has a source/drain 176 coupled to the light emitting diode 180, wherein the first transistor 170 is controlled by a first scan signal (SCAN1). The driving transistor 130 has source/drains 132 and 136. The source/drain 132 couples to a power source terminal 140 through the transistor 160, and the source/drain 136 couples to a source/drain 172 of the first transistor 170. The capacitor 150 couples a gate 134 of the driving transistor 130 to the power source terminal 140. When a second scan signal (SCAN2) is asserted, the second transistor 110 respectively couples the source/drain 172 of the first transistor 170 to the capacitor 150, and couples the gate 134 and the source/drain 136 of the driving transistor 130 together.
The pixel circuit also has a third transistor 190 controlled by the second scan signal to couple a data line 120 and the source/drain 132 of the driving transistor 130.
The drawback of the conventional pixel circuit is that it has five transistors (transistors 110, 130, 160, 170 and 190). These transistors reduce the aperture ratio of the pixel circuit.